The U.S. Food and Drug Administration (FDA) has declined to approve Dynavax Technologies' experimental hepatitis B virus (HBV) vaccine candidate with a toll-like receptor 9 adjuvant, stating it wants to see further data on safety in adults including seniors, the company announced this week.

Below is an edited excerpt from a recent Dynavax press release describing the FDA response in more detail.

Berkeley, CA -- February 25, 2013 -- Dynavax Technologies Corporation (NASDAQ: DVAX) announced today that it received a Complete Response Letter (CRL) from the U.S. Food and Drug Administration (FDA or Agency) regarding its Biologic License Application (BLA) for HEPLISAV, an investigational adult hepatitis B vaccine.

In the CRL, the FDA specified that the indication in adults 18-70 years of age cannot be approved without further evaluation of safety in this broad age group. The FDA also continues to express concern that novel adjuvants may cause rare autoimmune events. However, the Agency indicated its willingness to continue discussions regarding a more restricted use of HEPLISAV. Dynavax plans to discuss the CRL with the FDA to identify the most expeditious path to approval for HEPLISAV, particularly in adults who may receive the greatest benefit from HEPLISAV.

Furthermore, the FDA requested additional data from Dynavax's process validation program and clarifying information on the manufacturing controls and facilities related to the assurance of the quality of the commercial product. Dynavax believes it can provide the information but the exact timeframe for its response cannot be determined until it has met with the Agency.

Dynavax plans to meet with the FDA to discuss the steps necessary for potential approval of HEPLISAV and currently believes the meeting can take place within 6 weeks. Following its meeting with the FDA, Dynavax will provide updates as appropriate.

Dynavax's BLA was accepted for review by the FDA in June 2012. On November 15, 2012, the FDA's Vaccines and Related Biological Products Advisory Committee voted 8 to 5 with 1 abstention that there was insufficient data to adequately support the safety of HEPLISAV, although the Committee voted 13 to 1 that HEPLISAV data adequately demonstrated immunogenicity.

Dynavax's Marketing Authorization Application continues to be under review in Europe.